TRIGGERED STAR FORMATION IN A BRIGHT-RIMMED CLOUD (BRC 5) OF IC 1805

Fukuda, Naoya and Miao, Jingqi and Sugitani, Koji and Kawahara, Kentaro and Watanabe, Makoto and Nakano, Makoto and Pickles, Andrew J (2013) TRIGGERED STAR FORMATION IN A BRIGHT-RIMMED CLOUD (BRC 5) OF IC 1805. Astrophysical Journal, 773 (2). p. 132. ISSN 0004-637X. (doi:https://doi.org/10.1088/0004-637X/773/2/132) (The full text of this publication is not currently available from this repository. You may be able to access a copy if URLs are provided)

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Official URL
http://dx.doi.org/10.1088/0004-637X/773/2/132

Abstract

We report recent optical, near-infrared (NIR), and millimeter observations which have revealed some new features of the bright-rimmed cloud BRC 5 associated with W4. With slitless spectroscopy, we detected 17 Hα emission stars around the cloud; 4 are near the surface of the cloud, and 1 is toward IRAS 02252+6120. NIR photometry shows that the central Hα emission star, together with one bright infrared source, has large NIR excesses and Class I spectral energy distributions. These two Class I objects are associated with the 2.9 mm continuum peaks and with a bipolar outflow, and are in between two separate, elongated C18O(J = 1-0) cores. The C18O cores and the two Class I sources are aligned along a line at position angle ~240°, somewhat less than perpendicular to the direction of UV radiation from the OB stars. Most of the detected Hα emission stars, all T Tauri candidates, are located within ~3' of the cloud on the exciting star side. An estimate of the age of the stars based on a color-magnitude diagram suggests that these T Tauri candidates have ages of ~1 Myr or less, but are more evolved objects than the central young stellar objects. This age sequence suggests sequential star formation within the BRC 5 cloud. The 13CO(J = 1-0) emission shows three elongated structures, which indicates the asymmetric structure toward the UV incident axis. We present our exploratory simulation results by using a smoothed particle hydrodynamic code that suggests that the asymmetrical BRC 5 structure could possibly result from the evolution of a preexisting prolate molecular cloud subject to radiation-driven implosion (RDI). Our best-fit prolate cloud has an initial mass of ~400 M ☉, an axial ratio of ~1.7, and a semi-major axis of ~1.6 pc, pointing away from the ionization flux by an angle of 15°. The simulated cloud structure not only closely matches the observed asymmetric morphological structure of BRC 5, but also reveals the possibility of the development of two major cores at the head of BRC 5. For the first time, the possibility of forming two stars by an RDI mechanism in a BRC is investigated.

Item Type: Article
Additional information: number of additional authors: 6;
Uncontrolled keywords: ISM: clouds; ISM: individual objects (SFO 5); ISM: molecules; stars: formation; stars: pre-main sequence
Subjects: Q Science > QC Physics
Divisions: Faculties > Sciences > School of Physical Sciences
Depositing User: Stewart Brownrigg
Date Deposited: 07 Mar 2014 00:05 UTC
Last Modified: 20 Apr 2016 11:37 UTC
Resource URI: https://kar.kent.ac.uk/id/eprint/40529 (The current URI for this page, for reference purposes)
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